In light of this, there are prior art pneumatic distribution apparatuses used on automatic machines comprising rotary devices or carousels designed for handling components of products (such as for example single pick, movement, releasing in sequence) selectively activated with air using a rotary pneumatic distributor.
Usually, these carousels form parts of stations of automatic machines for forming products such as, for example, single use beverage capsules, in particular capsules for making extraction or infusion beverages such as coffee, tea, milk, chocolate or combinations of these ingredients.
The carousel comprises a body rotating about a vertical axis (or a horizontal axis, or even an axis inclined to the reference planes of the machine) from which a plurality of arms project radially; each of the arms is provided with an operating head equipped with, for example, blower means, for example for cleaning edges of the capsules, before successive steps for sealing portions of closing sheets on the edges, or for driving pneumatic pistons.
In a station comprising this carousel a pneumatic system is necessary for distribution of air under pressure so that it works in phase with the other parts of the machine or, in other words, that the air under pressure is only distributed during predetermined production steps, depending, for example, on the position of the arms, that is to say, of the operating heads between a starting point and an arrival point—and one or more transit points/stretches—which, in the case of rotary carousels, are points/stretches positioned along a closed circular path.
In order to optimise this type of pneumatic operation of the carousel, pneumatic rotary distributors are used which are substantially of two types: radial rotary dispensers and front rotary distributors.
However, both the radial rotary distributors and the front rotary distributors have drawbacks.
More specifically, the radial rotary dispensers have sealing problems, especially if they are used for paths which comprise active paths, that is, paths along which the operating heads are in communication with the source of air, alternated with non-active paths, that is, paths along which the operating heads are not in communication with the source of air.
The front rotary dispensers also have sealing problems. In detail, the prior art front rotary distributors comprise an annular element connected from a first part to a fixed frame which has a source of pressurised fluid and from a second part to a rotary body which has supporting arms for the operating heads.
Moreover, the annular element has one or more seats for receiving pins projecting from the fixed frame to prevent rotations of the annular element relative to the fixed frame.
Elastic elements (springs) are interposed between the annular element and the fixed frame to keep the annular element constantly in contact with the rotary body in a sealed fashion. In light of this, the annular element can move axially towards and away from the fixed frame. In the prior art front rotary distributors, the pressurised air pushes the annular element away from the rotary body, so that beyond a certain pressure value the elastic elements are no longer able to guarantee the contact between the annular element and the rotary body, with consequent lack of seal.
These radial rotary and front rotary distributors are also operated in suction mode. It is therefore possible to connect these distributors to a vacuum source, so that the operating heads can determine a suction at the active path, for example for retaining components of capsules, in phase coordination with other stations/elements of the automatic machine. However, these pneumatic distribution systems also have drawbacks.
In effect, the operating heads simultaneously present in the active path are in fluid communication with each other, so that malfunctions of an operating head at a given instant have a negative and immediate affect on the operating heads present in the active path in the given instant. In other words, if an operating head does not have, or loses, the respective component, the other operating heads present in the active path have an almost immediate suction drop such that it is sometimes no longer able to correctly retain the respective component.
Basically, the prior art rotary distributors do not guarantee independence of operation to the operating heads simultaneously present at a given instant along the active path.